Rotor for a rotary combustion engine

ABSTRACT

A rotor for a rotary engine, symmetrical about its central plane for ease of manufacture and adapted to having its registry gear installed on either side, rendering it suitable for installation at any rotor position in a multirotor engine.

United States Patent Steinwart [111 3,743,449 [451 July 3,1973

ROTOR FOR A ROTARY COMBUSTION ENGINE inventor: Johannes Steinwart, Bad Friedrichshall, Germany Assignees: Audi Nsu Auto Union Aktiengesellschait, Neckarsulm; Wankel Gmbl-l, Lindau, Bodensee, Germany Filed: Apr. 21, 1972 Appl. No; 246,417

Foreign Application Priority Data June 7, 1971 Germany P 21 28 235.9

US. Cl 418/39, 418/61, 418/94,

123/8.01 Int. Cl. F0lc 21/00, F030 3/00, F04c 1/06 Field of Search 418/39, 61, 94;

[56] Relerences Cited UNITED STATES PATENTS 3,323,712 6/196 7 Froede et al 4I8/6l 3,333,763 8/1967 Jungbluth et al. .Q 418/61 Primary Examiner-Carlton R. Croyle Assistant Examiner-Robert E. Garrett Attorney-Raymond P. Wallace et al.

[ 5 7] ABSTRACT A rotor for a rotary engine, symmetrical about its central plane for ease of manufacture and adapted to having its registry gear installed on either side, rendering it suitable for installation at any rotor position in a multirotor engine.

4 Claims, 1 Drawing Figure tation.

ROTOR FOR A ROTARY COMBUSTION ENGINE BACKGROUND or THE INVENTION This invention relates to a rotor for a rotary internal combustion engine of the trochoidal type, and more particularly to such a rotor having an internal cavity for flow of a cooling fluid, and rotatably mounted on an eccentric shaft within an engine housing. Each of the side walls of the rotor has a circular aperture therethrough, through one of which the registry ring gear is installed on the rotor hub, the cylindrical wall face of the other aperture serving as a sealing surface for outwardly expanding seal rings disposed on an eccentric portion of the shaft.

Rotors of this general type are known in the prior art, andexamples are shown in U. S. Pat. Nos. 3,323,712 and 3,323,713. In this known form of construction the diameter of the aperture in the rotor side wall on the gearwheel side is relatively great, because it must be large enough to admit passage of the ring gear which is mounted on the hub. On the other hand, the side wall aperture on the opposite side-cannot be made of equal diameter for constructional reasons. The outwardly acting seal rings which are carried in a groove on the eccentric portion of the shaft and which seal against the cylindrical wall face of the aperture cannot be made as large in diameter as the ring gear because it would necessitate enlarging the eccentric which bears them, thus adding greatly to the unbalanced mass of the shaft. The rotor of the prior art is therefore of nonsymmetrical design.

This nonsymmetrical design has various fabricational drawbacks. Since the rotor is a casting, the cores for producing the interior cavity of the rotor can only be made relatively weak, since the rotor side wall on the side opposite the gear has to extend radially inwardly to the diameter of the eccentric, that is, much further inwardly than on the opposite side. This also makes it difficult to clean the molding sand out of the hollow interior of the rotor, which must be perfectly done in order not to damage the tools in subsequent machining. It also renders difficult the machining of the hub, and is a hindrance in cleaning out machining chips, which must also be perfectly done in order not to damage the engine.

A further problem arises in the use of such a rotor. It is not possible to install the gear on the side having the smaller aperture, and in a multirotor engine the rotor gears cannot all be positioned on the same side of the rotors. Neither is it possible to turn the rotor over and install it in mirror-image fashion, since the rotor pockets are commonly arranged nonsymmetrically on the working faces of the rotor. In many engines the gas seals on the side faces of the rotor are also nonsymmetrical and cannot be used in the opposite direction of ro- SUMMARY 2 In the present invention the disadvantages of the.

prior art are overcome by providing a rotor having casting symmetry about the central plane of rotation. The

circular apertures in both side walls are of the same di-,

With such a rotor design in accordance with the invention the molding cores can be made considerably stronger and more stable than has heretofore been possible, resulting in less expensive castings. Because the interior cavity of the rotor is readily accessible axially from either side, cleaning out of casting sand, and of metal chips after machining, is greatly facilitated. Such greater accessibility of the interior results in greater ease in design and positioning of the casting cores, and therefore makes possible a widening of the rotor hub which is mounted on the eccentric, whereby the specific load on the bearing is decreased. Because of the symmetry about the central plane, the internal gear can be installed on either side, with the ring providing sealing surface on the opposite side, and thus the rotor can be used in any position in the engine.

The internal gear is fastened to the hub portion by screws, which are inserted through the hub from the opposite side. The screw heads are therefore covered by the ring providing sealing surface, and thus if any screw should loosen in service it cannot get free and damage the engine. The ring itself is preferably hollow and thin-walled, in order to decrease weight, and is preferably of U-shaped cross-section, so that it can be a simple part pressed from sheet metal.

It is therefore an object of this invention to provide a rotor for a rotary engine, symmetrical about the central plane of rotation.

It is another object to provide a hollow rotor having easy accessibility to the interior for cleaning of casting sand and machining chips.

A further object is to provide a rotor wherein the registry gear can be installed on either side.

Other objects and advantages will be apparent on reading the following specification in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE, DRAWING The drawing shows an axial cross-section of a rotor according to the invention, rotatably mounted on the eccentric of a rotary engine shaft.

DESCRIPTION OF A PREFERRED EMBODIMENT exterior of each of its working faces a recess or pocket 16. The peripheral wall 12 is connected by a substantially annular web 17 with a bored hub 18, the hub bore 7 having positioned therein a bearing 19. The web 17 is disposed on the median plane 21 between the two side walls, which isthe plane of rotation. The bearing 19 is positioned around an eccentric portion 22 of an engine shaft 23. To admit the eccentric to the interior of the hollow rotor, each of the side walls 13 and 14 is providedwith a central circular aperture 24 and 26 respectively, the apertures 24 and 26 being of equal diameter. The interior of the rotor has hollow spaces 27 through which flows a cooling fluid supplied by an axial bore 28 in the shaft which communicates-with a transverse bore 29 in the eccentric portion. A ring gear 30 is attached to the rotor hub, and is in engagement with a pinion (not shown) which surrounds the shaft 23 and is attached to a side wall (not shown) ofthe engine housing.

The ring gear is attached by screws 41 extending through the rotor hub from the opposite face.

Passage of cooling fluid out of the rotor hollow spaces 27 and into the operative chambers is prevented by seals which act between the eccentric and the rotor. On the gear side there is provided a disk 31 which is fastened to the eccentric by screws, the disk having a peripheral groove 32 in which is positioned at least one outwardly expanding seal ring 33, or preferably two such rings for more assured sealing. The seal rings 33 bear against the cylindrical face of the aperture 24 through side wall 13 of the rotor. At the side opposite the gear, sealing is accomplished by at least one outwardly expanding seal ring 34, and preferably two, disposed in a peripheral groove 36 in a prolongation 37 of the eccentric. The seal rings 34 act against the inner peripheral surface 38 of a ring 39 which is positioned in the aperture 26 through the side wall of the rotor. Ring 39 is preferably hollow, and may be of U-shaped crosss'ection so that it can be simply formed of sheet metal by drawing or stamping. The ring 39 may be pressed or shrunk into its position in the aperture.

By means of the arrangement of the ring 39 it is possible to make the two apertures 24 and 26 the same diameter, thus obtaining a rotor which is symmetrical relative to the middle plane 21. Because of the enlarged diameter of aperture 26 over the embodiments of the prior art, the molding cores which extend into the mold from this side to form the hollow spaces 27 can be made sufficiently stable and can be supported and held in place as readily as the cores entering from the gear side. The space 27 being readily accessible from this side, prior to installation of ring 39 the holding sand and the machining chips can be easily removed. Further, with this arrangement the ring gear 31 can be attached by screws 41 extending through the rotor hub, thus saving some space on the gear side which would otherwise be taken up by the bolt heads, and rendering the engine more secure from damage, since any bolt that might loosen nevertheless cannot come free, having its head held in place by the ring 39.

What is claimed is:

1. In a rotary internal combustion engine of the trochoidal type having a pair of side walls spaced apart by a peripheral housing to define an engine cavity and having a shaft transpiercing the engine side walls with an eccentric portion disposed within the engine cavity, a hollow liquid cooled rotor comprising in combination a peripheral rotor wall and a pair of parallel rotor side walls, each of the rr tor side walls having a central circular aperture therethrough, a generally annular web extending radially inwardly from the peripheral rotor wall midway between the rotor side walls and the rotor being formed generally symmetrically about the web, the web positioning a hub on the axis of the rotor and the hub being rotatably mounted on the eccentric portion of the shaft, an internal ring gear being mounted on the rotor at one side thereof and within the hollow interior, the rotor side wall apertures being of equal diameter and large enough to admit the ring gear, each of the apertures having a cylindrical inner surface, a disk-like member surrounding the shaft adjacent to the ring gear and having a circular groove in its outer periphery, at least one outwardly expanding seal ring disposed in the disk groove and cooperating with the inner surface of the rotor aperture on that side to provide sealing of the interior of the rotor, the rotor aperture on the opposite side having positioned therein an annular member having a cylindrical inner surface, the eccentric having in that region a circular groove in its periphery, and at least one outwardly expanding seal ring disposed in the eccentric groove and cooperating with the inner surface of the annular member to provide sealing of the interior of the rotor on the side opposite the internal gear. 7

2. A rotor as recited in claim 1, wherein the annular member positioned in the rotor aperture on the side opposite the internal gear is formed as a hollow element.

3. A rotor as recited in claim 2, wherein the hollow annular member is U-shaped in cross-section.

4. A rotor as recited in claim 3, wherein the internal ring gear is mounted on the rotor by screws extending through the rotor from the opposite side, the screw heads being covered by the midportion of the U-shaped cross-section of the annular member.

a: m a a: a 

1. In a rotary internal combustion engine of the trochoidal type having a pair of side walls spaced apart by a peripheral housing to define an engine cavity and having a shaft transpiercing the engine side walls with an eccentric portion disposed within the engine cavity, a hollow liquid cooled rotor comprising in combination a peripheral rotor wall and a pair of parallel rotor side walls, each of the rotor side walls having a central circular aperture therethrough, a generally annular web extending radially inwardly from the peripheral rotor wall midway between the rotor side walls and the rotor being formed generally symmetrically about the web, the web positioning a hub on the axis of the rotor and the hub being rotatably mounted on the eccentric portion of the shaft, an internal ring gear being mounted on the rotor at one side thereof and within the hollow interior, the rotor side wall apertures being of equal diameter and large enough to admit the ring gear, each of the apertures having a cylindrical inner surface, a disk-like member surrounding the shaft adjacent to the ring gear and having a circular groove in its outer periphery, at least one outwardly expanding seal ring disposed in the disk groove and cooperating with the inner surface of the rotor aperture on that side to provide sealing of the interior of the rotor, the rotor aperture on the opposite side having positioned therein an annular member having a cylindrical inner surface, the eccentric having in that region a circular groove in its periphery, and at least one outwardly expanding seal ring disposed in the eccentric groove and cooperating with the inner surface of the annular member to provide sealing of the interior of the rotor on the side opposite the internal gear.
 2. A rotor as recited in claim 1, wherein the annular member positioned in the rotor aperture on the side opposite the internal gear is formed as a hollow element.
 3. A rotor as recited in claim 2, wherein the hollow annular member is U-shaped in cross-section.
 4. A rotor as recited in claim 3, wherein the internal ring gear is mounted on the rotor by screws extending through the rotor from the opposite side, the screw heads being covered by the Midportion of the U-shaped cross-section of the annular member. 